NEW YORK (Reuters Health) - People suffering from creaky knees may want to give Tai Chi a try.

In a study, researchers found that practicing the Chinese mind-body exercise led to improvements in pain, function and even mental health for people with osteoarthritis of the knee. Some of these benefits persisted for a full year after the study began -- months after people had stopped doing the exercises.

"The Tai Chi group seems to have developed a general sense of well being, suggesting that there may be synergy between the physical and mental components of this discipline," note Dr. Chenchen Wang of Tufts University School of Medicine in Boston and colleagues in the journal Arthritis & Rheumatism. "These findings are promising because there are few efficacious long-lasting treatments for knee osteoarthritis."

Osteoarthritis of the knee is painful and disabling, and is becoming increasingly common as the population ages. While strengthening exercises are recommended for people with the condition, "these have modest benefits for pain and physical function and may not affect psychological outcomes," Wang and colleagues note.

Tai Chi has been shown to improve strength and balance, reduce pain, and ease depression and anxiety in people with chronic illness, the researchers add, but evidence on its benefits for people with knee osteoarthritis has been inconclusive.

To investigate further, they randomly assigned 40 people with knee osteoarthritis to an hour of Tai Chi or an hour of wellness education and stretching exercises twice a week for 12 weeks. Study participants' average age was 65, and three-quarters were women. Most were overweight.

No patients dropped out of the study and those in the Tai Chi group attended 85 percent of the sessions, while the control participants went to 89 percent of the sessions.

At 12 weeks, pain scores had improved by 75 percent, on average, for the Tai Chi group, while function had improved by 72 percent -- 57 percent and 46 percent greater than for the control-group patients, respectively.

The Tai Chi group also showed significant improvements in quality of life, "self-efficacy," and depression and anxiety compared to the control group, and the improvements in self-efficacy and depression persisted at week 24 and week 48. Self-efficacy refers to a person's belief that he or she can accomplish a goal.

These observations emphasize a need to further evaluate the biologic mechanisms and approaches of Tai Chi to extend its benefits to a broader population."